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Tom Rini83d290c2018-05-06 17:58:06 -04001/* SPDX-License-Identifier: GPL-2.0+ */
Darwin Rambo989ce042014-02-11 11:06:34 -08002/*
3 * Copyright 2013 Broadcom Corporation.
Darwin Rambo989ce042014-02-11 11:06:34 -08004 */
5
6/*
7 * Bitfield operations
8 *
9 * These are generic bitfield operations which allow manipulation of variable
10 * width bitfields within a word. One use of this would be to use data tables
11 * to determine how to reprogram fields within R/W hardware registers.
12 *
13 * Example:
14 *
15 * old_reg_val
16 * +--------+----+---+--+-----+----------+
17 * | | | | | old | |
18 * +--------+----+---+--+-----+----------+
19 *
20 * new_reg_val
21 * +--------+----+---+--+-----+----------+
22 * | | | | | new | |
23 * +--------+----+---+--+-----+----------+
24 *
25 * mask = bitfield_mask(10, 5);
26 * old = bitfield_extract(old_reg_val, 10, 5);
27 * new_reg_val = bitfield_replace(old_reg_val, 10, 5, new);
28 *
Codrin Ciubotariu8756de22015-07-24 16:55:25 +030029 * or
30 *
31 * mask = bitfield_mask(10, 5);
32 * old = bitfield_extract_by_mask(old_reg_val, mask);
33 * new_reg_val = bitfield_replace_by_mask(old_reg_val, mask, new);
34 *
Darwin Rambo989ce042014-02-11 11:06:34 -080035 * The numbers 10 and 5 could for example come from data
36 * tables which describe all bitfields in all registers.
37 */
38
39#include <linux/types.h>
40
41/* Produces a mask of set bits covering a range of a uint value */
42static inline uint bitfield_mask(uint shift, uint width)
43{
44 return ((1 << width) - 1) << shift;
45}
46
47/* Extract the value of a bitfield found within a given register value */
48static inline uint bitfield_extract(uint reg_val, uint shift, uint width)
49{
50 return (reg_val & bitfield_mask(shift, width)) >> shift;
51}
52
53/*
54 * Replace the value of a bitfield found within a given register value
55 * Returns the newly modified uint value with the replaced field.
56 */
57static inline uint bitfield_replace(uint reg_val, uint shift, uint width,
58 uint bitfield_val)
59{
60 uint mask = bitfield_mask(shift, width);
61
Codrin Ciubotariuc69abd802015-07-24 16:52:19 +030062 return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
Darwin Rambo989ce042014-02-11 11:06:34 -080063}
Codrin Ciubotariu8756de22015-07-24 16:55:25 +030064
65/* Produces a shift of the bitfield given a mask */
66static inline uint bitfield_shift(uint mask)
67{
68 return mask ? ffs(mask) - 1 : 0;
69}
70
71/* Extract the value of a bitfield found within a given register value */
72static inline uint bitfield_extract_by_mask(uint reg_val, uint mask)
73{
74 uint shift = bitfield_shift(mask);
75
76 return (reg_val & mask) >> shift;
77}
78
79/*
80 * Replace the value of a bitfield found within a given register value
81 * Returns the newly modified uint value with the replaced field.
82 */
83static inline uint bitfield_replace_by_mask(uint reg_val, uint mask,
84 uint bitfield_val)
85{
86 uint shift = bitfield_shift(mask);
87
88 return (reg_val & ~mask) | ((bitfield_val << shift) & mask);
89}